Recent studies have shown that reflexes and perception evoked by vestibular cues can utilize qualitatively different mechanisms; yet there is a paucity of knowledge regarding vestibular perception. This may be why large percentages of vestibular patients report perceptual deficits that are undiagnosed. Regardless of explanation, the underlying causes of many perceptual deficits are not diagnosed. With the exception of the subjective visual vertical test, quantitative clinical tests focus exclusively on reflexive responss. However, the best way to assay undiagnosed motion perception symptoms is via perceptual testing. Therefore, the primary goal for the research proposed herein is to develop new and improved methodologies to measure behavioral thresholds, in general, and vestibular thresholds, in particular. To achieve these goals, we propose theoretic analyses, numerical simulations, and some limited human testing. More specifically, to accomplish the above goals we proposal the following specific aims: Aim 1. Formally and explicitly apply signal detection theory to the measurement of behavioral vestibular thresholds. Aim 2. Develop, test, and verify improved analysis techniques for behavioral thresholds. Aim 3. Develop, apply, and verify automated computer adaptive methodologies for behavioral vestibular threshold data collection.